It is known that isopropenyl acetophenone is a compound useful as a starting material for the preparation of polyester resins, polycarbonate resins, polyurethane resins and the like which are excellent in physical properties, particularly heat resistance and mechanical strength, or as an additive for macromolecular materials or as a starting material for agricultural chemicals or pharmaceutical preparations.
For instance, triphenol type compounds can be obtained by the reaction of isopropenyl acetophenone with phenols, and the triphenol type compounds obtained are used at the time when polycarbonate resins are prepared.
However, isopropenyl acetophenone polymerizes to a certain extent when it is allowed to stand at room temperature, and it is extremely liable to polymerize when stored under the circumstances of high temperature. Because of its high polymerizability as mentioned above, isopropenyl acetophenone had such problems that a loss of isopropenyl acetophenone is incurred during storage thereof, or when other compounds are intended to be prepared by the use of isopropenyl acetophenone which has partially polymerized during storage thereof, the compounds obtained thereby come to deteriorate in quality.
Since isopropenyl acetophenone is liable to polymerize and difficult to store in the manner now described, utilization of isopropenyl acetophenone is markedly limited in present circumstances.
We conducted extensive researches with the view of obtaining stable isopropenyl acetophenone solutions which are capable of preserving the isopropenyl acetophenone contained therein for an extended period of time without causing polymerization thereof, and have eventually accomplished the present invention on the basis of our finding that isopropenyl acetophenone solutions containing specific compounds in combination with the isopropenyl acetophenone are quite stable.